Generally, amide compounds can dissolve a variety of compounds and are readily dissolved in water, and thus can be rinsed off with water. Therefore, amide compounds are envisaged to be used as solvents or detergents. For example, amide compounds can be used as a resist-remover, or as a special solvent for a poorly soluble resin such as polyimide or polyamide.
In particular, amide compounds are considered prospective alternative for solvents that are conventionally used frequently, including a halogen-containing solvent, and NMP (N-methylpyrrolidone) or a like solvent, since such a halogen-containing solvent has been reported to pose problems in terms of toxicity and environmental pollution (e.g., ozone layer destruction), and NMP or the like has been reported to have reproductive toxicity.
In consideration that an amide compound is used as a solvent or a detergent, availability of the amide compound at low cost is important. Therefore, demand has arisen for development of a method for effectively producing an amide compound on a large scale and at low cost, the amide compound being suitable for such an application.
For production of an amide compound suitable for use as a solvent or a detergent (e.g., a 3-alkoxycarboxylic acid-N,N-dialkylamide), production of an α,β-unsaturated carboxylic acid-N,N-dialkylamide is an important technique.
Hitherto known methods for producing α,β-unsaturated carboxylic acid-N,N-dialkylamides include, for example, a method for producing N,N-dimethylacrylamide (DMAA) by use of an acrylate ester, the method being disclosed in Patent Document 1, 2, or 3. However, this method firstly requires a step of esterifying acrylic acid and then requires a step of converting the ester group of the resultant ester compound into an amide group. Generally, conversion of an ester group into an amide group requires a polyol compound (e.g., glycerin) serving as a solvent. Therefore, the method requires, after completion of reaction, a step of separating a reaction product from the solvent. The method also requires, after completion of reaction, a step of separating an alcohol released from the ester compound, or an amine compound remaining in the reaction mixture. Thus, the aforementioned DMAA production method requires many steps. In view of production of an amide compound suitable for use as a solvent or a detergent, or an intermediate of the compound, the production method poses problems in terms of yield and cost.
The countercurrent contact method, which is generally employed during various reactions or purification, is known as a technique for yield improvement or effective production. For example, Patent Document 4 discloses a continuous production method for a cyclic formal; Patent Document 5 discloses a method for purifying a carboxylic acid amide; and Patent Document 6 or 7 discloses a method for producing urea.
There has been known a technique for controlling a reaction employing a compound having a double bond, by inhibition of polymerization. For example, Patent Document 8 discloses a method in which a polymerization inhibitor (e.g., a combination of a thermal polymerization inhibitor such as phenothiazine and a compound having a nitroso group) is added directly to a distillation vessel; Patent Document 9 discloses a method in which nitrogen oxide, serving as a gas exhibiting a polymerization inhibition effect, is caused to flow during distillation; Patent Document 10 discloses a method in which a polymerization inhibitor (e.g., an N-nitrosophenylhydroxylamine salt) that generates, through decomposition, multiple components exhibiting a polymerization inhibition effect is added to a vessel or a reflux portion; and Patent Document 11 discloses a method for preventing polymerization of an N-substituted-(meth)acrylamide during distillation thereof, which method does not affect the quality of a final product.